1. Field of the Invention
This invention relates to a packaging machine for producing reclosable packages, and more particularly, to a sealing station and a welding station for installing resealable closures or zippers onto packages produced on a form-fill-and-seal (FFS) packaging machine. The invention further relates to retrofitting horizontal FFS packaging machines to incorporate the zipper installing function.
2. Background Information
The formation of packages on form-fill-and-seal machines takes many forms. There is a spectrum of form-fill-and-seal packaging machines which extends from horizontal and vertical bag-forming machines which form packages from a single web of packaging material to rollstock machines which form packages by sealing an upper web to a formable lower web. Such machines package an unending array of consumable goods, including food products, non-food products, and medical products.
While the sealing and channel-forming die assembly of this invention may be broadly applicable to packaging machines, the information herein is presented in the milieu of a horizontal, rollstock form-fill-and-seal machine, especially those which provide for packaging of products in a vacuum or a modified atmosphere. These machines make thermoformed packs which are most commonly used for foods, such as sliced meats and cheeses. A further consideration here is seal integrity and this becomes critical as such products most often require vacuum or modified atmosphere packing.
In recent years many thermoformed packages are popularly supplied with primary and secondary closures, one of which is resealable. The resealable closures, commonly known as sealable profiles or zippers, have been marketed under such trademarks as Fresh-Loc and Zip-Pac. While the resealable closure has wide consumer acceptance, the requisite machine adaptation to the rather bulky closure (as compared to film) has been problematic. Typically because of their geometry and other inherent problems, the incorporation of resealable closures into a package frequently creates wrinkles in one packaging film or the other resulting in incompletely sealed packages. These incompletely sealed packages or leakers, in which a loss of seal integrity is experienced, are frequently not detectable by the quality control of the packager, but become apparent later in the distribution channel. When packaged goods without seal integrity get to the marketplace or into the consumer""s hands, such goods have a reduced shelf life or experience spoilage.
In the past, horizontal FFS machines installed zippers at a separate working station between the forming station and the evacuation and sealing station. The zipper installing work station had a dedicated lifting device associated therewith. The zippers provided in the form of spooled zipper blanks, when exposed to the high temperatures of the zipper installation stations, tended to twist out of alignment becoming difficult to manage and frequently causing the wrinkling of the packaging film described hereinabove.
The following patents are known to the inventors and are presented for the further discussion of the prior art:
The development of technology in the consumer goods and food packaging area is driven by three distinct technologic/economic forces, namely, (1) manufacturers of goods/food producers requirements; (2) packaging film/zipper blank innovation; and, (3) packaging machine development. In the first category, the patent application assigned to Sargento Foods, Inc., U.S. patent application Ser. No. 20020015537; and the patent assigned to Oscar Mayer Foods Corporation, U.S. Pat. No. 4,782,951 are primary examples. In the packaging film innovation area, the patents assigned to Reynolds Consumer Products, U.S. Pat. No. 5,198,055 and to W. R. Grace and Co., Cryovac Division, U.S. Pat. Nos. 4,240,241 and 4,437,293 are discussed.
In the following, it is seen that the prior art packaging machine patents arise from two main streams of technological development, namely, the Illinois Tool Works, Inc., Glenview, Ill. products and the Multivac Sepp Haggenmuller KG, Wolfertschwenden, West Germany, (Multivac) products. The Illinois Tool Works line includes the Minigrip, Inc. technology, which corporation is now part of Illinois Tool Works, Inc. It is noted that the reclosable seal patents to Griesbach et al. of Oscar Mayer Foods Corporation and Wirth et al. of Reynolds Consumer Products, Inc., are related to the Multivac technology.
U.S. patent application Ser. No. 20020015537xe2x80x94Strand et al. (Sargento Foods, Inc.)xe2x80x94Feb. 7, 2002
This application describes a resealable bag for a food product which is manufactured by an HFFS packaging machine such as described in Sanborn, U.S. Pat. No. 4,240,241 (W. R. Grace and Co.) and also has a tamper-evident seal.
U.S. Pat. No. 6,138,439xe2x80x94McMahon et al. (ITW)xe2x80x94Oct. 31, 2000
The patent describes an HFFS packaging machine which mounts a zipper to film extensions of an already sealed package at a zipper and slider insertion and attaching station dedicated. After installation of the zipper, a slider is separately inserted into the assemblage.
U.S. Pat. No. 5,198.055xe2x80x94Wirth et al.xe2x80x94Mar. 30, 1993
Wirth et al. discloses a method of forming a reclosable package using special profile strips (zipper components), the strips and a resulting package. The profile strips have a flange element which includes, by being a thickened element or by adding a buffer strip thereto, a thermal barrier. The barrier is designed to prevent the flanges from fusing together during the installation step of flange-film sealing.
U.S. Pat. No. 5,118,203xe2x80x94Andronico, D. (T. W. Kutter, Inc.)
The apparatus of this invention is an HVFFS Tiromat 3000 manufactured by Kramer and Grebe (Canada) Ltd., Waterloo, Ontario, which employs a zipper application assembly prior to the forming, filling and sealing functions.
U.S. Pat. No. 5,105,603xe2x80x94Natterer, J. (Multivac)xe2x80x94Issued Apr. 21, 1992
The patent to Natterer describes a rollstock HVF-F-S packaging machine having a work station dedicated to applying the closure strip to the lower formable web prior to entering the sealing and evacuation where the package is mated with the lidstock, evacuated and sealed. The work station for applying the closure strip is not temperature controlled.
U.S. Pat. No. 4,782,951xe2x80x94Griesbach et al.xe2x80x94Nov. 8. 1988
The patent to Griesbach et al. discloses a resealable package having interlocking closure strips outside of a hermetic seal. The seal is of a peelaway type so as not to destroy the integrity of the package upon opening of the package.
Griesbach et al. discloses a reclosable package comprising interlocking closure strips positioned outside of a hermetic seal or seal area and the method for producing same. The hermetic seal is of the easy-open or peelaway type so as to not destroy the integrity of the package or closure strips upon opening of the package.
U.S. Pat. No. 4,296,588xe2x80x94Vetter (Multivac)
This patent discloses a sealing station for a HVFSS which provides a deflector to divert the air and moisture removed from the product-containing receptacle and thereby improve the vacuum achieved during the evacuation cycle.
U.S. Pat. No. 4,240,241xe2x80x94Sanborn, P. A. (W. R. Grace and Co.) Dec. 23, 1980
The patent describes a thermoform machine for packaging a product in a reclosable package in a straight through process on a single machine rather than making a reclosable pouch on one machine and performing the filling, evacuating and sealing process on another machine.
U.S. Pat. No. Re.: 28,969xe2x80x94K. Naitoxe2x80x94Sep. 21, 1976
The patent discloses a reclosable plastic bag having interlocking rib and groove elements integral with the plastic of the bag with the elements being designed so that the bag opens easily from the outside, but resists opening from the inside.
U.S. Pat. No. 4,876,842xe2x80x94Ausnitxe2x80x94Oct. 31, 1989
A method of and apparatus for packaging product masses in a form, fill and seal machine, wherein a continuous length of packaging film is joined in running relation by a continuous length of separately formed plastic reclosable fastener assembly having interlock profile strips spot sealed together at package length intervals. The corunning fastener strip assembly and the packaging film are oriented so that the spot seals of the strip are located in alignment with the spaces between the product masses on the film to assure that the fastener strip assembly will be cross sealed at the spot seals when the film is cross sealed between the product masses to provide individual packages. The orienting may be effected by an indexing arrangement including sensor response to index marks on the film and the fastener assembly.
In reviewing the prior art as described hereinabove, the zipper installation procedures are not conducted at the sealing station simultaneously with the sealing and/or evacuation functions. Present zipper installation procedures frequently interfere with package integrity. It is not taught how to sufficiently isolated the zipper installation from the sealing function so as to avoid the introduction of air into product receptacles, thereby reducing product shelf life and the overall quality of the packaged goods. Unlike what is known to date, in the disclosure which follows, it is taught how the sealing and evacuation function, is combined at the work station with zipper blank feeding and tacking function. Moreover, the teaching includes how to stabilize the zipper blank during processing by controlling the temperature conditions under which installation takes place. The submission of the above list of documents is not intended as an admission that any such document constitutes prior art against the claims of the present application. Applicant does not waive any right to take any action that would be appropriate to antedate or otherwise remove any listed document as a competent reference against the claims of the present application.
In general terms, the invention disclosed hereby is a form-fill-and-seal (FFS) packaging machine wherein a resealable closure or zipper is attached to the package simultaneously with the sealing station operation of the packaging machine and thereafter is welded in place at the zipper welding station. For this function, a zipper blank feeder and a channel-forming die with an impulse sealer are integrated with the sealing die of a packaging machine, which combination forms an improved working station that is utilizable with a broad spectrum of FFS machines. Because the packaging machine, when modified with the present invention, installs the zipper to the package at an existing working station, an additional lifting device is not required. This enables the retrofitting of FFS packaging machines to include a zipper attachment function without changing the footprint of the packaging machine.
The sealing and channel-forming assembly of this invention creates an aperture between and a pathway through two layers of packaging film (on a horizontal FFS packaging machine, between a thermoformed lower web and a lidstock or upper web) for the zipper blank. While the sealing die typically provides a perimeter seal about the lid, an impulse sealer in the channel-forming die functions cooperatively with the lift station associated with the sealing die to attach the zipper to the layers of packaging film. Upon completion of the package, this attachment portion, if retained, becomes the tamper-indication portion of the package seal.
The sealing and channel-forming assembly and the zipper welding and package cutting station of this invention are of jacketed construction enabling the temperature control of zipper blank throughout the installation procedures described hereinbelow. Installing the zipper under temperature controlled conditions facilitates the management of the zipper blank.
After passing through the sealing station, the package indexes to the the zipper welding and package cutting station. Here, the packaging films are longitudinally welded to corresponding zipper flanges and the zippers are transversely welded at both ends thereof. The package cutting operation separates the packages as required.
The present invention also is novel as it enables the retrofitting of existing packaging machine lines by, in contrast to present practice of having a working station and lift device for installation of a zipper, incorporating a zipper blank feeder and a channel-forming die with an impulse sealer into the sealing station and a zipper welding unit into the cutting station. Both the sealing station and the welding and cutting station operate under temperature-controlled conditions.
It is an object of the present invention to provide in a form-fill-and-seal packaging machine, a channel-forming die for use in installing resealable closures.
It is another object of the present invention to provide a resealable closure installation device for a horizontal rollstock machine that during installation isolates the product package from the closure being installed.
It is yet another object of the present invention to provide a resealable closure installation device for a horizontal rollstock machine that during installation maintains the vacuum or modified atmosphere under which the goods are packed.
It is still yet another object of the present invention to adapt a rollstock form-fill-and-seal machine for resealable closure installation using a minimum number of lift stations.
It is another feature of the present invention that the resealable closure is installed on the package under temperature-controlled conditions.
It is a feature of the present invention that the resealable closure being installed is tacked to the packaging films at the sealing station die.
It is another feature of the present invention that the resealable closure is installed on the package without affecting the seal integrity thereof.
It is yet another feature of the present invention that the resealable closure installation device may be retrofitted to a form-fill-and-seal machine without increasing the number of lift stations.